Phil's PDP10 Miscellany Page

I cut my teeth on DEC10's, first in high school, using the BOCES/NCODE
KA10 (S/N 109) timesharing system on Long Island (via an ASR33 and an
acoustic coupler), and then on KL1282 (running 6.03A and 7.01) as
[1300,1523] and [301,273] at Stevens Tech, in lovely Hoboken, NJ. I
was also a tourist on the MIT ITS systems as BUDD (a typo that stuck).
From Stevens I took a job working on FORTRAN-10/20 at DEC Marlboro
(using, KL1026/1042 as [31,5732], KL2137, MRFORT and others as
<BUDNE>). When I left DEC, I managed the Boston University
Computer Science 2060 (KL3047) as BUDD@BUCS20.ARPA at until it's
demise in October 1986, when I became a full-time Unix person.

A great joy of using (and working on) DEC software was the focus on
quality that simply doesn't exist in todays world. DEC's corporate
culture was somewhat leaden, so the software wasn't always feature
laden, but we took great pride in what we produced.

The flexibility (and hardware documentation) made the '10 a hotbed of
research Operating Systems. BB&N created TENEX, and The major Computer
Science Universities had their own Operating Systems: MIT had ITS,
Stanford AI had WAITS, and CMU had a customized TOPS-10. All three
later ran TOPS-20 systems, as did Rutgers, Utah and many others.

The first
network e-mail
was sent between two BB&N PDP-10's running TENEX.

The '10 was the center of Hacker culture, back when the word was high
praise. PDP-10 assember was the Lingua Franca. The
Jargon file, --MORE-- processing, EMACS,
HAKMEM,
"job control", and ZORK all originated from the MIT PDP-10
community.
A great deal of software was available in source form, both from
DECUS, the DEC users group, shared via mailed magtapes and on the
ARPAnet.
The PDP-6/10 community was preceeded by the PDP-1
community (which was preceeded by the TX-0
and
TMRC communities)!
Part I ("The True Hackers") of Steven Levy's book "Hackers: Heroes of
the Computer Revolution" (the first
two chapters
of which are available via
Project Gutenberg).
Fred Hapgood's "Up the Infinite Corridor" has a chapter on TMRC.
Another book to consult may be: Architects of the Information Society:
Thirty-Five Years of the Laboratory for Computer Science at MIT by
Simpson Garfinkel (MIT Press, 1999).

PDP-10 20th (1984) Anniversary Memerobilia

The PDP-6 was born in 1964, 1984 was the 20th Anniversary, the last
major anniversary when 36-bit engineering was still going strong.

20th Anniversary Booklet

At Alan Kotok's retirement, Alan and Rosanne autographed it for me
(I briefly worked the code scheduler for VAST, the VAX to SAFE
Translator). SAFE was a 64-bit VAX datatype compatible RISC project
than Alan headed, before Cutler stole the project, renamed it PRISM
along with all the instructions (so that they used PDP-11/VAX
conventions to name the datatypes, so the native 64-bit load (LOAD64)
became "load quadword", and they moved the dedicated zero register
from R0 to R64). PRISM died, along with HL32, a 32-bit RISC project
(named after the Hudson, Mass site at which it was being developed).
However, it seems the developers of the Alpha AXP architecture were
aware of PRISM.
Some allege that the AXP stood for
Almost
eXactly Prism

1984(?) LCG Group Photo

Photograph by David Dyer-Bennet
of the DEC Large Computer Group (LCG) in Marlboro,
Mass (in front of building MR-1). (Photo taken for the 20th
anniversary of 36-bit computing in 1984?) We don't know the exact
date, but it was before June 23, 1984!

(click on photo to enlarge.
NOW WITH IMAGE MAP AND NAMES!!

New! DD-B found and scanned (with better resolution) the
original slides
which include a different shot from the same session,
as well as seperate shots of smaller groups.
Dan Murphy found
photos he took
of the shoot, including "behind the scenes" shots".
Another 1984 photo of the
TOPS-20 group
(in suits!) which has a few folks who were away at the time of
the above picture. There are more links to sites with photos
in the documentation section of this page.

This is a copy of a page that used to hang in (later day TOPS-10
wizard) Jim Flemming's cube in MR1-2/L12. From
The Book of the Weird,
by Barbara Ninde Byfield, 1973, Dolphin Books, page 149.

Legend reads;

TRUST those Wizards who are thin and fine drawn.
Mighty muscles, ruddy cheeks, and genial dispositions bespeak Wizards
who when Apprentices and young men sneaked out to play instead of
applying themselves to long days over hot crucibles and long nights
pouring over scrolls, tomes, tablets and tracts.

TW in RH20 Land

Printed booklet of (latter day TOPS-10 Wizard) Tony Wach's struggle to
adapt TOPS-10 to use the KL10's RH20 "internal channel" massbus
controller. (can anyone tell me when this was printed, and for what
occasion?)

(click to enlarge)

Cover reads:

Tony in RH20 Land
-or-
I should have Listened When my Mother Told
Me There Was A Great Future in Encyclopedia Sales
by
Anthony Wachs who once said,
"Answer that, it may be the phone."

TECO 124:
DEC TECO 24 modified at Stevens Tech, University of Texas Austin,
University of New Orleans, ....

The Incompatible Timesharing System

Developed by PDP-6 hackers, who originally didn't want a timesharing
system, ITS took an interesting approach to security; No operations
were privileged (although many were certainly obscure). Sensitive
operations were logged to the printing console. Guests accounts were
available to "Tourists". Rather than make breaking the system a
challenge, potential miscreants were encouraged to make postive
contributions.

WAITS

Marc Crispen wrote:

WAITS most advanced display support of all, not duplicated even
today. Last shared code with TOPS-10 in 3.54 days, but
was extensively hacked even then. Filesystem and device
drivers were completely different (most reliable
filesystem of any PDP-10 OS, the result of the world's
worst hardware). Lots of funky devices.

Tymcom-X

Tymshare's TYMCOM-X Operating System was based on the TOPS-10 Monitor,
version 5.02C. It had some TOPS-20 features added, such as
memory-mapped disk I/O with all disk structures based on a 512-word
page instead of a 128-word block.

Other

Hardware

PDP-6

The PDP-6 project started in early 1963, as a 24-bit machine. It grew
to 36-bits to better support LISP. The PDP-6 was implemented using
transistors on large "system modules". The price in 1964 of a PDP-6
system was $300,000, (CPU $120K) and could execute 250,000
instructions per second. Gordon Bell was the architect, Alan Kotok
was the assistant logic designer. The PDP-6 designed to be used as a
multiprocessor, and it's CPU had a seperate option number: Type 166.
Gordon Bell wrote:

"The PDP-6 was designed for timeshared computation and real-time
laboratory use with straightforward interfacing. At the initiation of
the project, three timeshared computers were operational: a PDP-1 at
Bolt Beranek, and Newman (BB&N) which used a high-speed drum that
could swap an image in one 34ms revolution; an IBM 7090 system at MIT
called
CTSS,
which provided each of 32 users a 32 Kword environment;
and an AN/FSQ-32V at SDC which could serve 40 simultaneous
users"

Design input for the PDP-6 came from MIT PDP-1 users including John
McCarthy, Marvin Minsky and Peter Samson. Only 23 PDP-6's were built,
and they were difficult to manufacture.

KA10

The KA10 (1967) CPU was a reimplementation of the asynchronous PDP-6
design using smaller modules and improved manufacturing. In order to
convince management to make another shot at a large system, just about
everything was optional: including fast memory for the accumulators,
and the second set relocation/protection registers, floating point,
and byte instructions. The minimum configuration, the 10/10 with 8K
of memory and only paper tape (no DECtapes) was priced at $99,000.
Oxford actually bought one of these (though they did have to buy more
memory). Performance was improved to 380,000 instructions per second
(1.5x the PDP-6) at a price of $150K for the CPU.

MAXC had to be bug-for-bug compatible with the PDP-10's floating point
instructions in order to run LISP (under TENEX). It used early iNTEL
dynamic memory chips instead of core. The MAXC was somewhat faster
than the KA10, and much more reliable (running more than 2000 hours
between crashes more than once). Two were built, each operated for
about 9 years.

After finishing the MAXC design, the PARC team started on the Alto,
the prototype bitmap display & mouse driven workstation.

Other Computer History Links

The PDP-6/10 were part of a lineage that started at MIT in the 1950's;

Whirlwind

Project Whirlwind (operational in 1951) pioneered real-time
interaction, the use of CRT displays and core memory. To test
Whirlwind's core memory, a special system, the Memory Test Computer
(MTC) was built by a team headed by Ken Olsen who had just graduated
from MIT. Whirlwind engineers went on to develop computers at MIT
Lincoln Laboratory in Lexington Massachusetts. Whirlwind was adopted
USAF for use in the SAGE (Semi-Automatic Ground Environment) air
defense system.

Other future DEC engineers who worked on Whirlwind and at Lincoln Labs,
included Ben Gurley, Dick Best, Harlan Anderson, Stan Olsen, and Bob
Savell.

TX-0

The TX-0 was the first (zeroeth) transistorized computer, designed and
built at MIT Lincoln Labs in 1956 to test transistor circuit designs
and a 64KW, tube driven (S) memory for the TX-2 (The first computer
designed, the TX-1 was rejected as too complicated, a step backward
resulted in the TX-0). This echoed the development of the Whirlwind
MTC.

TX-0 was designed by Wesley Clark (who would later design the LINC,
which spawned LINCtape, which spawned DECtape -- DEC later sold the
LINC, and integrated it with the PDP-8, first in the LINC-8, and later
the PDP-12). TX-0 had an 18-bit word, a 5 MHz clock, and a 6
microsecond cycle time (it execute 83,000 additions per second). It
used 3,500 Philco L-5122 fast surface barrier transistors (later
commercially available as the 2N240) costing $80 each. TX-0 consumed
1000 watts, covered 200 square feet, and cost 3 million dollars to
develop. Ken Olsen was in charge of constructing TX-0, and the
display system (with light pen) was designed by Ben Gurley (who later
designed the PDP-1). Memory design and fabrication were done by
Richard (Dick) Best and Jack Mitchell.

The original TX-0 used 2-bits for order (op) codes and 16 for addressing.
The four instructions were: Store memory (sto x), Add memory to
accumulator (adx), Transfer on Negative Accumulator (trn x), the
last was a microprogramming Operate command.

In July 1958 TX-0 was loaned to the MIT Research Laboratory of
Electronics (RLE) with a transistor driven 4K word (T) memory. It
lived in room 26-248, and was managed by Jack Dennis who extended the
machine (by borrowing now unused address bits), increasing number of
opcode bits from 2 to 5, doubling the memory to 8K words, and adding
an index register. The TX-0 later inspired the design of the PDP-1.
The TX-0 was used nearly 24 hours a day as a personal computer; by day
it was used by researchers (Gordon Bell used it as a member of the
Speech Research Group). Free time was used by "Hackers", many from
the Tech Model Railroad Club (TMRC). Software implemented on TX-0
included word processing, sound recording, speech recognition, and
music synthesis. Jack Dennis developed a macro assmbler named MACRO
and an interactive symbolic debugger called FLIT (FLexowriter
Interrogation Tape), named after a common household fly sprayed by a
hand-pumped atomizer (or "Flit Gun"). Robert Saunders wrote the first
MIDAS assembler.

Gordon Bell acquired the TX-0 as part of the DEC Computer Museum where
is was operated November 13th, 1984 at a TX-0 reunion, afterwards it
moved to the Boston Computer Museum, and is now at the
Computer History Museum in
California.

PDP-1

After working on the TX-0 and TX-2, Ken Olsen founded Digital
Equipment Corporation (DEC) in 1957, which at first manufactured only
"system
modules" patterned on circuits first designed for the TX-0. While
the company was founded with the explicit goal of producing computers,
the company's backers felt the company should first establish a
business building modules.

The PDP-1 (Programmed Data Processor) was DEC's first computer (but they
didn't want to call it one), built in 1960. 50 were built and sold
for $120,000 with 4K of 18 bit memory. The PDP-1 was designed by Ben Gurley
using DEC's system modules, had a 5 microsecond cycle time.
BB&N purchased the second machine
built, a prototype, right off the floor of the 1959 Joint Computer
Conference in Boston (The whole show was abuzz about this fledgling
company and its little machine which cost less than $150,000). DEC
gave an early system to MIT, where it was installed in a room next to
the TX-0. MIT, BB&N and Stanford all implemented Time Sharing systems
for their PDP-1's. (BB&N's was implemented by Sheldon Boilen under
the supervision of John McCarthy).

At MIT Alan Kotok wrote the first DDT (named by Peter Samson?) for the
PDP-1, a follow on the the TX-0 MicroFLIT debugger. Text processors
included the Colossal Typewriter (by John McCarthy and Roland Silver),
Expensive Typewriter (by Steve Piner, and extended by Peter Deutsch),
the first
TECO
(written by Dan Murphy in 1962).
The text formatter "Justify" by Peter Samson and
was followed by
TJ-2,
(which all fed into the CTSS
TYPSET and RUNOFF
programs).
The MIDAS assembler was ported to the PDP-1 over a weekend by a team
of hackers. Peter Samson wrote a music compiler and player. Jack
Dennis implemented hardware extensions to the PDP-1, and implemented a
timesharing system for it.

The follow on to the PDP-1 was the PDP-4 (1962), with a goal of
producing a smaller cheaper 18-bit system. Gordon Bell wrote "The
PDP-4 took half the space of the PDP-1 and provided 5/8 the
performance for 1/2 the price". The PDP-4 was not software compatible
with the PDP-1 (but could use it's peripherals). The PDP-7 (1964) was
conceived as a repackaged PDP-1, but since DEC had created a larger
software library for the PDP-4, the PDP-7 implemented the PDP-4
architecture. The PDP-7 was followed by the PDP-9 (1966) and PDP-15
(1969). The majority of these systems were used for Process Control,
Lboaratory, and Real Time applications.

TX-2

The follow-on to TX-0, the 36-bit TX-2 became operational in 1958
(after Ken Olsen left). It was used to advance the state of the art
in AI and man-machine interaction. It is most famous for the
Sketchpad program by Ivan Sutherland which allowed a user to create
and manipulate and resize sketches on the display by using a light
pen. The TX-2 later ran timesharing, and in October 1965, the TX-2
exchanged the first packets with the AN/FSQ-32 at
System Development Corp. in Santa Monica, California over a dedicated
1200bps line in an ARPA funded experiment. TX-2 was later on the ARPAnet.

Other Time Sharing Systems

Project Genie/SDS 930/SDS 940/BCC

Project Genie (1964-1969) at the University of California, Berkeley
was funded by ARPA (contract SD-185) to produce a timesharing system.
They started with the 24-bit SDS 930, and added modifications (which
were later commercialized as the SDS 940). Several ARPA sites
purchased SDS 940's, including BB&N, where it influenced the design of
TENEX.

An offshoot of Project Genie was the Berkeley Computer Company
(1968-1970), whose BCC 500 featured SDS 940 compatibility. Many BCC
people were hired by Xerox'es Palo Alto Research Center (PARC), where
the first computer they built was MAXC, a PDP-10
clone.

AN/FSQ-32V ["Q-32"] TSS

The AN/FSQ-32V
was built by IBM for military purposes. It had a 48 bit word and 18
bit addresses. A spare system at System Development Corp. in Santa
Monica, California ran an early timesharing system "TSS" funded by
ARPA in 1963. The Q32 at SDC was never equipped with more than 48K
words.

Dartmouth Time Sharing System (DTSS)

Time-Sharing project started in September 1963 by Dartmouth professors
John Kemeny and Thomas Kurtz. Ran on a
Datanet-30 "Master" which served as front-end for communications,
control, and scheduling, and a GE-235 back end. Began operations in
May 1, 1964 at 4AM, by executing
BASIC
programs from two terminals simultaneously (both were "PRINT 2+2"). A
fast one-pass ALGOL-60 compiler, a machine-language interpretive
program DIP, and and editor EDIT were also available.
Dartmouth Time Sharing System Reborn